1. Field of the Invention
The present invention relates to hermetic compressors having positive displacement liquid lubricant pumps to supply liquid lubricant to bearing surfaces. More specifically, the present invention relates to compressors including liquid lubricant pumps having cavities disposed within the pump and drive shaft to trap debris by magnetic and centrifugal force.
2. Description of the Related Art
Compressor lubrication systems often include a positive displacement lubrication pump to supply liquid lubricant to bearing surfaces within the compressor. Liquid lubricant, or oil, often contains debris in the form of metallic particles circulating throughout the lubrication system. The particles detrimentally affect bearing surfaces by causing premature wear, and consequently, compressor performance is compromised. It is known to provide cartridge type or screen filters to capture debris, however an inherent disadvantage of cartridge and screen filters is that they clog and consequently block circulation of oil to bearing surfaces which significantly shortens the life of the compressor. Responsive to this clogged filter effect, compressor assemblies have been adapted with bypass valving, for example, which routes the oil around the filter when the filter becomes clogged to effectively maintain an adequate oil supply to the bearing surfaces. However, the circulating oil remains debris-laden which may cause an abrasive attack on the bearing surfaces resulting in bearing seizure and imminent failure of the compression mechanism.
Hermetic compressor assemblies are susceptible to oil-entrained debris, the most destructive being the fine powdered debris, which may not be captured by standard cartridge and filtering methods. The fine powders entrained in the oil are often composed of ferrous material which is attracted to a magnet. While previous compressor assemblies have utilized magnets to attract entrained metallic particles, these compressors have proven to do so inefficiently. Typically, magnets are randomly placed within the interior of the compressor housing, producing marginal particle accumulation performance. Therefore, the marginal benefits provided by these types of compressors, in view of the substantial costs associated with installing magnets to attract ferrous particles, have limited their practicality.
Further, with evolving and more demanding environmental standards, the hydrocarbon based oils and refrigerants traditionally used are yielding to environmental friendly substitutes. However, it is not fully understood whether these substitute lubricants are equally effective in providing comparable levels of lubrication and durability to the compressor mechanism. Thus, improving the ability to remove foreign particles from liquid lubricant, without a substantial compressor assembly cost increase, would be highly desirable.
Yet another problem associated with the use of impeller type pumps in compressor assemblies is one of drive shaft misalignment, relative to the pump housing, during the assembly process. Traditionally, misalignment of the drive shaft and pump housing was avoided by providing the pump housing, compressor mechanism assembly and impeller pump assembly with precise tolerances. A significant labor and handling cost is associated with parts having precise tolerances. What is desired is an impeller type pump assembly structure which requires significantly less labor to manufacture and assemble compared to previously employed structures.
An inexpensive oil pump assembly which includes the ability to trap debris suspended in the oil while continuously providing an ample supply of oil to bearing surfaces is highly desired. Further, an oil pump assembly which provides further cost reduction attributable to avoiding precise part tolerances in preventing drive shaft and pump housing misalignment is desired.
The present invention overcomes the disadvantages of prior compressor assemblies by providing a hermetic compressor assembly which includes a compressor housing including a quantity of liquid lubricant therein, a compressor mechanism provided within the compressor housing, a drive shaft selectively rotatable and operably connected to the compressor mechanism, a liquid lubricant displacement element engaged to the drive shaft and a support member attached to the compressor housing, a pivotable magnetic member provided between the liquid lubricant displacement element and the support member provided with a suction port therein. The liquid lubricant displacement element is in fluid communication with the quantity of liquid lubricant through the suction port in the magnetic member. At least a portion of any ferrous particles contained in the liquid lubricant are attracted to and retained by the magnetic member as the liquid lubricant is passed through the suction port of the magnetic member.
The present invention further provides a hermetic compressor assembly including a compressor mechanism and a quantity of liquid lubricant provided in a compressor housing, a selectively operable drive shaft driveably connected to the compressor mechanism, a liquid lubricant displacement element supported by a support member and engaged to the drive shaft. The compression mechanism and the liquid lubricant displacement element are in fluid communication through a passage provided in the drive shaft. A centrifugal particle trap cavity is defined by a wall of the passage within the drive shaft and a portion of the liquid lubricant displacement element. A magnetic member is pivotably supported by the support member and a thrust member is superposed with the magnetic member. A magnetic particle trap cavity is provided within a lateral face of the thrust member and is partially enclosed by a lateral surface of the magnetic member. The liquid lubricant is urged from the sump to the compression mechanism through the passage in the drive shaft and any debris in the liquid lubricant is successively retained by the magnetic particle trap cavity and the centrifugal particle trap cavity prior to the lubricants introduction to the compression mechanism.